In a conventional wireless communication system, a desired signal interferes with a signal of another system, which may result in deterioration of a communication environment.
For example, in BS (Broadcasting Satellite) reception facilities having a BS antenna installed at each home, frequency conversion is often used to process a received signal. At that time, if radio waves leak from the reception facilities, interference may occur in a band of a cellular phone system.
A signal band of satellite broadcasting which becomes an interference signal is wider than the band of the cellular phone which is a desired signal and, thus, it is difficult to remove the interference signal by a filter or the like.
If the interference signal is already known, it is possible to generate a replica as a reference and remove the interference signal. However, when a replica of the interference signal cannot be prepared, it is difficult to remove only the interference signal.
When the interference signal cannot be removed, the communication quality of a cellular phone which is a desired signal deteriorates.
When the interference signal is a leakage signal from a BS antenna, an interference signal is steadily transmitted from a fixed place. When the desired signal is a signal of a cellular phone, the desired signal is intermittently transmitted from various places.
In other words, a communication environment in which the interference signal is steadily present and the desired signal is intermittently present is obtained.
As for a conventional noise canceller device, there is known “noise canceller device” disclosed in Japanese Patent Application Publication No. 2015-170877 (Hitachi Kokusai Electric Inc.: Patent Document 1).
Patent Document 1 discloses a technique for acquiring information on interference signals received by a plurality of sub antennas by performing correlation processing of the interference signals, combining the received interference signals based on the information, acquiring information on the interference signals included in the received signal by performing correlation processing of a signal received by a main antenna and the combined signal, generating an interference signal replica based on the information, and removing the interference signals by subtracting the interference signal replica from the received signal.
Patent Document 1: Japanese Patent Application Publication No. 2015-170877
However, the conventional noise canceller device does not sufficiently consider the accurate and stable removal of the interference signals in an environment where the interference signal is steadily present and the desired signal is not steadily present.